Shower valve seat insert

Hello and thanks for your replies!

My Price Pfister 3 Valve shower unit had a valve seat in it - that is until I tried to remove the entire hot water stem assembly. Being a novice DIY I think that the stem was in full closed position, meaning the stem was actually extended as far outward as it could be cranked. This was an attempt to shut off the slow and steady trickle of water that could not be stopped. When I turned the whole stem with a deep socket wrench it was very stiff. This was probably because the elongated stem was jammed tight against the seat. The with-all-of my-strength turning of the whole stem actually turned the seat with it - and cracked the threads that the seat goes on to into a number of pieces that fell off. It seems that there is a fairly smooth rim that is the place where an insert sits to have female threads to accept the seat. This insert appears to have been put on to the smooth rim at the factory. The insert goes around 80% around the whole smooth room. I would gues that the insert is bent into a smaller circle, placed on the rim, and then allowed to expand back to a full cilcle encompassing (most of) the smooth rim. This insert does not appear anywhere on Price Pfister valve schematics or parts catalog. How can I possibly obtain this insert to have female threads for the valve seat - and how do I put it on? Can calling Price Pfister help?

Please help - my shower has no hot water now!

Thank you and have a wonderful holiday!

Mark